Drill bits are commonly used for drilling bore holes or wells in earth formations. One type of drill bit is a fixed cutter drill bit which typically includes a plurality of cutting elements, or cutters, disposed within a respective cutter pocket formed within one or more blades of the drill bit and one or more nozzle sockets formed within the drill bit.
FIGS. 1 and 2 show a drill bit 100, or fixed cutter drill bit 100, in accordance with the prior art. Referring to FIG. 1, the drill bit 100 includes a bit body 110 that is coupled to a shank 115 and is designed to rotate in a counter-clockwise direction 190. The shank 115 includes a threaded connection 116 at one end 120. The threaded connection 116 couples to a drill string (not shown) or some other equipment that is coupled to the drill string. The threaded connection 116 is shown to be positioned on the exterior surface of the one end 120. This positioning assumes that the drill bit 100 is coupled to a corresponding threaded connection located on the interior surface of a drill string (not shown). However, the threaded connection 116 at the one end 120 is alternatively positioned on the interior surface of the one end 120 if the corresponding threaded connection of the drill string, or other equipment, is positioned on its exterior surface in other exemplary embodiments. A bore (not shown) is formed longitudinally through the shank 115 and extends into the bit body 110 forming a plenum 310 (FIG. 4), which communicates drilling fluid during drilling operations from within the bit body 110 to a drill bit face 111 via one or more nozzle sockets 114 formed within the bit body 110. These nozzle sockets 114 are cylindrically shaped within the drill bit 100.
The bit body 110 includes a plurality of gauge sections 150 and a plurality of blades 130 extending from the drill bit face 111 of the bit body 110 towards the threaded connection 116, where each blade 130 extends to and terminates at a respective gauge section 150. The blade 130 and the respective gauge section 150 are formed as a single component, but are formed separately in certain other drill bits 100. The drill bit face 111 is positioned at one end of the bit body 110 furthest away from the shank 115. The plurality of blades 130 form the cutting surface of the drill bit 100. One or more of these plurality of blades 130 are either coupled to the bit body 110 or are integrally formed with the bit body 110. The gauge sections 150 are positioned at an end of the bit body 110 adjacent the shank 115. The gauge section 150 includes one or more gauge cutters (not shown) in certain drill bits 100. The gauge sections 150 typically define and hold the full hole diameter of the drilled hole. Each of the blades 130 and gauge sections 150 include a leading edge section 152, a face section 154, and a trailing edge section 156. The face section 154 extends from one end of the trailing edge section 156 to an end of the leading edge section 152. The leading edge section 152 faces in the direction of rotation 190. The blades 130 and/or the gauge sections 150 are oriented in a spiral configuration according to some of the prior art. However, in other drill bits, the blades 130 and/or the gauge sections 150 are oriented in a non-spiral configuration. A junk slot 122 is formed, or milled, between each consecutive blade 130, which allows for cuttings and drilling fluid to return to the surface of the wellbore (not shown) once the drilling fluid is discharged from the nozzle sockets 114 during drilling operations.
A plurality of cutters 140 are coupled to each of the blades 130 within a respective cutter pocket 160 formed therein. The cutters 140 are generally formed in an elongated cylindrical shape; however, these cutters 140 can be formed in other shapes, such as disc-shaped or conical-shaped. The cutters 140 typically include a substrate 142, oftentimes cylindrically shaped, and a cutting surface 144, also cylindrically shaped, disposed at one end of the substrate 142 and oriented to extend outwardly from the blade 130 when coupled within the respective cutter pocket 160. The cutting surface 144 can be formed from a hard material, such as bound particles of polycrystalline diamond forming a diamond table, and be disposed on or coupled to a substantially circular profiled end surface of the substrate 142 of each cutter 140. Typically, the polycrystalline diamond cutters (“PDC”) are fabricated separately from the bit body 110 and are secured within a respective cutter pocket 160 formed within the bit body 110. Although one type of cutter 140 used within the drill bit 100 is a PDC cutter; other types of cutters also are contemplated as being used within the drill bit 100. These cutters 140 and portions of the bit body 110 deform the earth formation by scraping and/or shearing depending upon the type of drill bit 100.
For steel bits, the nozzle sockets 114 are machined into the drill bit 100. Nozzle sockets are formed using apparatuses and methods known to people having ordinary skill in the art and will not be described in detail herein for the sake of brevity.
FIG. 3A shows a cross-sectional side view a nozzle 210 coupled within the nozzle socket 114 in accordance with the prior art. FIG. 3B shows a top view of the nozzle 210 coupled within the nozzle socket 114 in accordance with the prior art. Referring to FIGS. 3A-3B, the nozzle socket 114 includes a nozzle socket base 230 and a nozzle socket wall 235 extending perpendicularly away from the perimeter of the nozzle socket base 230, thereby forming a cylindrically-shaped cavity 237 therein. Hence, the nozzle socket 114 also is cylindrically shaped. The nozzle 210 is inserted through the nozzle socket 114 and coupled to the bit body 110 (FIG. 1) adjacent the nozzle socket base 230. Although not illustrated, the nozzle 210 is coupled to the bit body 110 (FIG. 1) using a snap-fit, threaded connection, or other method and/or device known to people having ordinary skill in the art.
As previously mentioned, the bore is formed within the shank 115 and extends into the bit body 110 forming the plenum 310. FIG. 4 shows flow paths from the bit 100 to nozzle sockets 114. The bore allows for drilling fluid to flow from within the drill string into the drill bit 100. The flow tubes 320 in the bit body allow drilling fluid to flow from within the plenum 310 to nozzle sockets 114. In the embodiment shown in FIGS. 1 and 2, the fluid reaching the nozzle sockets is sprayed into the well by the nozzles 210. The spray of drilling fluid through the nozzle 210, which are positioned at the drill bit face 111, facilitates removal of the cuttings from the drill bit face 111 and moves them back towards the surface of the ground. The nozzle sockets 114, as previously mentioned, are often cylindrically shaped, i.e., have a nozzle socket wall 235 that forms a cylindrical shape. Although four nozzle sockets 114 are illustrated as being formed within the drill bit 100, greater or fewer nozzle sockets 114 are formed in other drill bits 100.
During drilling of a borehole, the drill bit 100 rotates to cut through an earth formation to form a wellbore therein. This cutting is typically performed through scraping and/or shearing action according to certain drill bits 100, but is performed through other means based upon the type of drill bit used. Drilling fluid (not shown) exits the drill bit 100 through one or more nozzles 210 and facilitates the removal of the cuttings from the borehole wall back towards the surface. As the drill bit 100 rotates and the drilling fluid with cuttings are at the bottom of the borehole, some cuttings adhere to the drill bit 100 causing inefficiencies. Thus, the nozzles 210 facilitate removal of portions of these cutting that are adhered to the drill bit 100.
High angle nozzles, or high angle nozzle sockets, also known as lateral jets, are known in the drill bit casting art. However, they are difficult to incorporate into machined bits, such as steel bits, due to the constraints in the manufacturing process.
The drawings illustrate only exemplary embodiments of the invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.